public class Test {
    class TreeNode{
        public char val;
        public TreeNode left;
        public TreeNode right;

        public TreeNode(char val) {
            this.val = val;
        }
    }

    public boolean isSameTree(TreeNode p, TreeNode q) {
        if(p == null && q != null || p != null && q == null){
            return false;
        }
        if(p == null && q == null){
            return true;
        }
        if(p.val != q.val){
            return false;
        }
        return isSameTree(p.left,q.left) && isSameTree(p.right,q.right);
    }
}
